Forced draft refrigerator



Jan. 24, 1967 J. s. BOOTH FORCED DRAFT REFR IGERATOH Filed Sept, 23, 1965 F IG. 2

INVENTOR JOHN S. BOOTH BY (an;

ATTORNEY FIG. I

United States Patent ()fifice Patented Jan. 24, 1967 This application is a continuation-in-part of application Serial No. 394,122, filed September 3, 1964, now abandoned. The present invention relates to refrigeration, and more particularly relates to an improved refrigerator box construction having forced air circulation.

As is well-known in the art, refrigerators heretofore manufactured, particularly those of the type used in commercial establishments such as food stores, restaurants and the like, which have no freezing compartment, erri'ploy'an insulated box having a front access door to a series of horizontally-spaced wire grille shelves. The cold air, customarily introduced to the box at a point near the top, circulates from top to bottom through the grille-like shelves. These refrigerators usually employ afan located adjacent the top rear of the box to blow cold air from the rear of the box outwardly toward the door. The cold air then passes downwardly through the grille-type shelves adjacent the door to the bottom of the box. In some refrigerators the fan is reversed such that warm air is withdrawn from the top of the box and forced through the cooling coils and then expelled downwardly along the back wall to rise upwardly along the door. In either type of refrigerator, the cold air is blown from the box when the door is opened. This materially reduces the efiiciency of the refrigerator. To combat this loss of cold air from the box, it is common practice to utilize a switch actuated by the opening of the door so as to de-energize the fan and thereby terminate circulation of the cold air. However, the relatively tall column of heavy cold air still tends to spill from the refrigerator as it falls unrestricted through the grille-like shelves, and stopping the circulation of air at frequent intervals also materially reduces the overall efficiency of the system. Another undesirable feature of this type of system is that the grille-like shelves are difficult to clean and must usually be removed from the box before adequate cleaniug can be accomplished.

Therefore it is an important object of the present invention to provide a more eflicient refrigerator.

Another object of the invention is to provide an improved system for circulating cold air in such a manner that loss of the cold air when the door is opened is reduced to a minimum.

Yet another object of this invention is to provide a refrigerator wherein the cold air may be circulated continuously without excessive loss when the door is open.

A further object of the invention is to provide a re frigerator construction which utilizes solid shelves which may be more easily cleaned and which provide a more stable support for small articles which might be placed in the refrigerator.

Still another object of the invention is to provide a refrigerator construction wherein the cooling coils are located at the bottom of the box to provide increased usable space.

Yet another object of the invention is to provide a refrigerator wherein the shelves are kept at a more uniform temperature.

The foregoing and other objects are accomplished by means of a refrigerator box construction wherein substantially solid, horizontally-disposed shelves divide the insulated box of the refrigerator into a plurality of vertically-stacked compartments. Cold air is force-circulated by introducing the air at one side of each of the compartments and withdrawing the air from an opposite side of each compartment. The cold air thus flows horizontally through the several compartments of the box and, rather than being directed at the door, is directed parallel to the door. Further, the column of cold air standing in the box is segregated into separate compartments so that the height of the column of cold air avail able to drive the air from the bottom of the door is materially reduced, even when air is circulated with the door open. This materially increases the efficiency of the refrigerator system.

In accordance with a more specific aspect of the invention, the cooling coils of the refrigeration cycle are disposed below the insulated compartment. Air is forced through the coils, up through a duct disposed in one wall, and out through orifices in one side wall into each of the compartments. The air is withdrawn from the compartments through orifices in the opposite side wall and returned downwardly through the opposite wall to the cooling coils. The stream of cold air is divided in a predetermined ratio between the various compartments by a suitable control means to obtain efficient cooling. This is accomplished by grading the size of the inlet and return flow orifices leading to the various compartments as will hereafter be described in greater detail.

A better understanding of the invention, its objects and advantages may be had from the following detailed description taken in conjunction with the drawings, wherein:

FIGURE 1 is a perspective view of a refrigerator constructed in accordance with the present invention; and,

FIGURE 2 is a perspective view similar to FIGURE 1 with the front portion of the refrigerator broken away to better illustrate details of construction.

Referring now to the drawings, a refrigerator construced in accordance with the present invention is indicated generally by the reference numeral 10. The refrigerator 10 comprises an insulated box 12 having an access door 14 in the front vertical side wall. The components of a refrigeration system such as the compressor, condenser, and associated components may be disposed within the lower portion 16 of the refrigerator which is covered by a grille 18 or at the back side of the box. The cooling coils of the refrigeration system are indicated generally by the reference numeral 20 and are disposed in an air circulation path which will presently be described.

The insulated box may conveniently be comprised of an outer shell 22, a layer of insulation 24, and an interior shell 26. The shells 22 and 26 may conveniently be fabricated from sheet aluminum, and the insulation 24 may be. of any suitable type such as one of the synthetic foam insulating materials.

A first vertical air duct 28 is formed between the interior shell 26 and a side wall 30. A second vertical air duct 32 is formed between the interior shell 26 anl the opposite interior side wall 34. A bottom wall 36 interconnects the bottoms of the side walls 30 and 34 and is spacedfrom the lower portion of the interior shell 26 to provide an air duct 38 in which the cooling coils 20 are disposed. The duct 38 communicates with the vertical air duct 28. A squirrel cage type blower 62 draws air downwardly through the return flow duct 32, and forces it through the cooling coils 20 and upwardly 3 through the duct 28. Three substantially solid, horizontally-disposed shelves 4%), 42, and 44 divide the interior of the refrigerator box into four vertically-stacked compartments. Inlet orifices 46, 47, 48 and 49 in the side wall 30 provide communication between the air duct 28 and the four compartments. Return flow orifices 54, 55, 56, and 57 in the side wall 34 provide communication between the compartments and the return duct 32.

Thus it will be noted that a forced circulation of air is accomplished wherein air is forced by the blower 62 through the cooling coils 2t) and upwardly through the air duct 28. The cold air then passes through the inlet orifices 46-49 into the four compartments. The cold air passes horizontally across the bottom 36 and the shelves 40, 42 and 44 and through the return flow orifices 54-57 into the return flow duct 32. Thus it will be noted that the movement of the cold air through the compartments is parallel to the opening of the door 14. Therefore, when the door is opened, the inertia of the cold air tends to limit the air which spills rather than assisting in forcing the cold air out of the box as in the prior refrigerator boxes. This is enhanced by the fact that air is also sucked from the compartments by the blower through the return flow orifices and return flow duct. Further, the shelves 40, 42 and 44 materially reduce the height of the column of cold air and thereby reduce the pressure differential tending to cause the cold air to flow out of the box. These factors combine to materially reduce the loss of cold air when the door is opened and therefore contribute to the efficiency of the refrigerator. The solid shelves formed by the bottom wall 36 and the shelves 40, 42 and 44 are considerably easier to clean than the grille-type shelves heretofore used, and provide a more stable base upon which small items may be placed. If desired, the shelves 40, 42 and 44 may be provided with small apertures so that condensation will tend to drain from the respective shelves to the bottom of the box without permitting appreciable circulation of the cold air through the openings.

It will be noted that the cold air stream passing over the coils is divided into four separate streams which are passed through the separate compartments. The separate streams are then rejoined in the return fiow conduit 32 prior to passing through the blower 62. It will also be noted that the lengths of the flow paths of the four separate streams become increasingly greater through the successively higher compartments. Further, the suction of the blower and the flow of the air through the return flow duct produce considerably greater suction at the lower return flow orifice than at the top return flow orifice. Since it is usually desirable to obtain uniform cooling throughout the box, the percent of the total volume of cold air passed through each of the compartments should be approximately equal to the percent the volume of each respective compartment is to the total volume of the box. Therefore, the orifices 46-49 and 54-57 may be varied to effect an equal division, or a division in substantially any desired ratio. However, in accordance with an important aspect of the invention, where the compartments are of substantially equal volume and are to be maintained at the same temperature, and equal division of air is accomplished by increasing the inlet orifices 46-49 in area from bottom to top at a substantially uniform rate, and decreasing the area of the return flow orifices 54-57 at a uniform rate from bottom to top. Thus, the interior walls of the box have input orifices therethrough which are graded in size in a first sense with distance from the blower and return orifices therethrough which are graded in size with distance from the blower as to control the volume of air through each compartment. Due to the suction in the return flow duct 32, the return flow orifices 54-57 change at a lower rate than the inlet orifices 46-49. The bottom return flow orifice 54 is of larger area than the bottom inlet orifice 46, while the top return flow orifice 57 is of smaller area than the top inlet orifice 49.

In one embodiment where the shelves 40, 42, and 44 were about 26 inches wide and 23 inches deep the orifices were sized as follows:

Orifice: Height, inches 46 A 47 /2 48 A 49 1 /2 54 1 55 56 4 57 /2 If the volumes of the several compartments are not equal, or if it is desired to maintain the compartments at different relative temperatures, then the inlet and return flow orifices may be varied in another manner so as to control the volume of cold air passing through each compartment.

From the above description of a preferred embodiment of the invention, it will be evident to those skilled in the art that a forced air circulation refrigeration system has been described which materially reduces the loss of cold air when the door to the refrigerator box is open. Further, the circulation is such that the blower 62 may be operated when the door is open without a significant increase in the loss of air. The several shelves within the refrigerator may be more uniformly maintained at a desired temperature, or may be selectively maintained at different temperatures, merely by varying the size of the inlet and return flow orifices. The solid shelves are much easier, to clean and provide a more stable base for small items. The same system may be used in a multidoor refrigerator box of the type used in food stores or in restaurants, and in general, the larger the box the more significant the saving in cold air by use of the forced air circulation system described.

Although a preferred embodiment of the invention has been described in detail, it is to be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is:

1. A forced air refrigerator comprising:

an insulated box having an access door and opposite interior side walls,

a plurality of substantially solid shelves extending horizontally across the interior of the box between the side walls and dividing the box into a plurality of vertically-stacked compartments,

an air blower disposed adjacent the bottom of the box,

a first air duct extending from the output side of the blower upwardly along one of said interior walls and communicating with each of the compartments through a separate inlet orifice formed in said one interior wall which orifice increases in area from bottom to top,

a second air duct communicating with each of the compartments through a return flow orifice, the return flow orifices decreasing in area from bottom to top, and extending downwardly along the other of said interior walls to the intake side of the blower, and

a refrigeration system having a cooling coil disposed in the air path for cooling the air as it is circulated from the blower through the first duct, through the inlet orifices, across the compartments, through the return flow orifices, and through the second air duct to the input of the blower.

2. The combination set forth in claim 1 in which the inlet orifices change in area from bottom to top at a rate which is greater than the rate of change in outlet orifices.

3. A forced air refrigerator comprising:

an insulated refrigerator box having an access door and interior walls,

a plurality of substantially solid shelves extending horizontally across the interior of the box and 5 dividing the box into a plurality of compartments,

an air blower,

a first air duct extending from the output side of the blower vertically along one interior wall and communicating with each of the compartments through 10 an input orifice formed in the interior wall,

a second air duct extending from the intake side of walls and communicating with each compartment the blower vertically along another of the interior through a return flow orifice,

said interior walls having input orifices therethrough which are graded in size in a first sense with distance 6 from said blower and return orifices therethrough which are graded in size in a second sense opposite said first sense with distance from said blower as to control the volume of air through each compartment, and

means for cooling the air as it is circulated from the output of the blower through the first air duct, the compartments and the second air duct back to the input side of the blower.

References Cited by the Examiner UNITED STATES PATENTS 1,397,392 11/1921 Amend 62-255 2,788,641

4/1957 Franklin 62419 WILLIAM J. WYE, Primary Examiner. 

1. A FORCED AIR REFRIGERATOR COMPRISING: AN INSULATED BOX HAVING AN ACCESS DOOR AND OPPOSITE INTERIOR SIDE WALLS, A PLURALITY OF SUBSTANTIALLY SOLID SHELVES EXTENDING HORIZONTALLY ACROSS THE INTERIOR OF THE BOX BETWEEN THE SIDE WALLS AND DIVIDING THE BOX INTO A PLURALITY OF VERTICALLY-STACKED COMPARTMENTS, AN AIR BLOWER DISPOSED ADJACENT THE BOTTOM OF THE BOX, A FIRST AIR DUCT EXTENDING FROM THE OUTPUT SIDE OF THE BLOWER UPWARDLY ALONG ONE OF SAID INTERIOR WALLS AND COMMUNICATING WITH EACH OF THE COMPARTMENTS THROUGH A SEPARATE INLET ORIFICE FORMED IN SAID ONE INTERIOR WALL WHICH ORIFICE INCREASES IN AREA FROM BOTTOM TO TOP, A SECOND AIR DUCT COMMUNICATING WITH EACH OF THE COMPARTMENTS THROUGH A RETURN FLOW ORIFICE, THE RETURN FLOW ORIFICES DECREASING IN AREA FROM BOTTOM TO TOP, AND EXTENDING DOWNWARDLY ALONG THE OTHER OF SAID INTERIOR WALLS TO THE INTAKE SIDE OF THE BLOWER, AND A REFRIGERATION SYSTEM HAVING A COOLING COIL DISPOSED IN THE AIR PATH FOR COOLING THE AIR AS IT IS CIRCULATED FROM THE BLOWER THROUGH THE FIRST DUCT, THROUGH THE INLET ORIFICES, ACROSS THE COMPARTMENTS, THROUGH THE RETURN FLOW ORIFICES, AND THROUGH THE SECOND AIR DUCT TO THE INPUT OF THE BLOWER. 